Mahzarin R. Banaji was starting out as an assistant professor of psychology at Yale University in the late 1980s, at a time when women professors were scarce enough that administrators eager to offer a class on the psychology of gender turned to her. Banaji had no expertise in the area; her research focused on memory. But she said she would do it, and she quickly found herself inhabiting the overlapping worlds of gender studies and psychology.

Banaji was fascinated by a memory study by psychologist Larry Jacoby. He had asked people to read a list of names from the phone book, such as “Sebastian Weisdorf,” and rate how easy they were to pronounce. A day later, those same people were handed a list of names that included famous people, others from the phone book, and some names from the list they had read the day before. Asked which were famous people, the study participants incorrectly classified Sebastian Weisdorf and others, whose names they had learned just the day before, as famous.

What, Banaji wondered, would happen if the name was Susannah Weisdorf? She did the test and found that female names were far less likely to achieve fame in the same way. When she grilled participants later, it occurred to no one that gender might be a factor.

That study was a seed, which grew into an idea in psychology that has become transformative: Everyone carries with them implicit biases that may change how people perceive or interact with others.

Today, millions of people have taken the Implicit Association Test that Banaji, Anthony G. Greenwald of the University of Washington, and Brian Nosek of the University of Virginia developed to reveal those unconscious biases. Banaji, now a psychology professor at Harvard University, has with Greenwald written a book, “Blindspot: Hidden Biases of Good People,” describing the origins and development of the influential idea.

Q: What are your own biases?

A: The first experience I had with the IAT [Implicit Association Test] was very disconcerting. I mean, I was quite certain that if I took a black-white test, to associate black and white with good and bad, I was certain that I would come out associating black with good. . . . It was stunning for me to discover that my hands were literally frozen when I had to associate black with good. . . . So the first thought that I had was: “Something’s wrong with this test.” Three seconds later, it sunk in that this test was telling me something so important that it would require a reevaluation of my mind, not of the test.

Q: If we all have them, what can people do about these biases?

A: I would say we should not be naive about how easily we can change them. On the other hand . . . there are studies that show when you are confronted with an opposite association from the one you are usually used to seeing, it will shift you in some way. . . . At its heart, the test is telling us something about ourselves that is not palatable. . . . You go have a cholesterol test or a hypertension test and it tells you [that] you have something in your body of which you could not have been aware. It’s not your fault, but once you know, a smart person will do something differently.